Construction in trench of pipelines and similar operations



April 16, 1968 A. R. $.MORRICE 3,377,805

CONSTRUCTION IN 'TRENCH 0F PIPELINES AND SIMILAR OPERATIONS 7 Filed Jan. 28, 1966 5 Sheets-Sheet 1 HIYTPONY0NOLU 56'DTOIV moRMcs INVENTOR:

April 16, 1968 A. R. SPMQRRICE 3,377,305

CONSTRUCTION IN 'IRENCH' OF PIPELINES AND SIMILAR QPERATIONS Filed Jan. 28, 1966 3Sheets-Sheep 2 INVENTOR: ANTI/0N) RONALD SeAToN Momuce A ril 16, 1968 A. R. s. MORRICE I 3,377,805

CONSTRUCTION IN TRENCH OF PIPELINES AND SIMILAR OPERATIONS Filed Jan. 28, 1966 3 Sheets-Sheet 5 INVENTOR:

ANTHONY RONALD $flTON MORE/CE United States Patent ABSTRACT OF THE DISCLOSURE A trench shoring frame which comprises a pair of opposed side walls and a plurality of cross members extending between these side walls, the side walls and the cross members defining a working zone communicating between the top, bottom and forward end of the frame, a back fill compactor wall which is adapted to be inclined and which extends transversely to the direction of the spacing of the side walls, and a plurality of jacks urging the compactor wall against back fill to compact the fill until the resistance causes continued expansion to thrust the shoring frame and working Zone forward. The side plates are tapered to form a cutting edge. A chute may be detachably connected to the thrust plate to return part of the material which is dug from the trench for placement in the space in the trench behind the thrust plate. The side plates of the shoring frame house horizontally disposed members, one for each jack assembly, and these side plates may be provided with removable vertical members which are detachable for passing over obstructions. A vacuum source may be connected to well connections at the side plates.

This invention relates to the constructions of pipelines or other work in trench and is particularly concerned with the support of the trench sides whilst pipes are laid or other work carried out; the return to the trench as fill and the compaction in the trench of the material previously excavated; and the removal of ground water from the trench whilst work is in progress.

Most trench work in Great Britain is carried out by the use of mechanical excavators fitted with back acter or hoe equipment. Deep trenches, often approaching 20 feet are common and the support of the trench sides using this method and means of excavation presents a problem which has not hitherto been satisfactorily solved.

Men setting trenches are continually exposed to danger and timber sufiiciently strong to withstand the full ground loads which may be encountered is cumbersome and expensive to handle.

- The problem is aggravated by the conventional practice of depositing the excavated spoil along the edges of the trench in preparation for the refilling operation, since this superimposed load adds considerably to the normal ground loads and to the size of the timber needed for safe working.

There are a large number of trench collapses every year and consequently the accident and fatality rate among men employed in this section of the construction industry is very high indeed.

After pipes have been laid or other work carried out, trenches are normally refilled with the spoil originally excavated. Ideally, the refilling should be carried out in thin layers with each layer punned using hand-operated or mechanical rammers, and the degree of such compaction should approach or be equal to that of the undisturbed ground so that ground movement is prevented and settlement of the trench is kept to a minimum. In practice this filling and ramming is difiicult and costly and in deep trenches a satisfactory degree of consolidation is seldom 3,377,896 Patented Apr. 16, 1968 ice obtained except after a long period of natural settlement.

In work in permeable strata where the trench to be formed will lie below the normal water table, it is customary to lower the water table as work proceeds by the use of well point or similar dewatering equipment. This normally involves the jetting vertically into the ground ahead of-the work of a number of well points, and this jetting, together with the subsequent extraction and reinsertion is expensive and laborious. This is particularly so where suction heads exceed about 16 feet and Where two stage working is required.

It is therefore the object of the present invention to provide means to mechanise the operations of timbering, refilling, compacting, and dewatering and to carry them out more effectively, more cheaply and less laboriously. In its preferred form the said means is powered from an excavator of suitable type carrying out the trench excavation and is operated by the driver of this machine.

This has been made practicable by recent developments in trench work and pipeline construction which are as follows:

(l) The development of high-powered hydraulically operated back acters with long reach arms and wrist actionbucket operation which make available an adequate and convenient source of power, enable spoil to be excavated from the face of a trench and deposited without spillage, and enable the trench to be excavated with a vertical or undercut face.

(2) New specifications and also pipe manufacturers and safety recommendations which now advocate the refilling of trenches as soon as practicable after pipes have been laid, and the use in many circumstances of permeable granular material for pipe bedding.

According to one aspect of the present invention, a method for the construction of pipelines or other work in trench, the method comprising the steps of forming a small section of the required trench or excavation by any suitable means, setting into said section means which are held in spaced-apart relationship, moving said means progressively along the trench against side loads and there after forming the remainder of the trench or excavation between or ahead of said means.

The method also comprises the further steps of returning directly to said section the spoil taken from that section being formed, compacting the returned spoil, utilising the resistance of the returned and compacted spoil for the movement of said means and further compacting the returned spoil by utilising the resistance of the trench face.

The method comprises the further step of removing ground water by the progressive insertion of well points mounted within said means.

According to a second aspect of the present invention, apparatus for use in the construction of pipelines or other work in trench includes a rigid thrust plate carrying one or more pressure-operated members adapted, upon the application of pressure thereto, to move progressively along the trench means Which are held in horizontal spaced-apart relationship.

The apparatus consists basically of two side shields set vertically and in contact with the trench sides The side shields are of sufiicient area and structural strength to resist the full ground loads which may be encountered and are held rigidly in spaced-apart relationship by substantial cross-members which are so placed as not to obstruct the digging action of the excavator.

The side shields and cross-members which support them form a rigid shoring frame which upon the application of sutficient force may be moved forward along the trench as it is excavated, against the side loads imposed by the ground pressures. Men laying pipes or carrying out other work in the trench may do so in safety within the protection of this shoring frame. A

Force is applied to the frame via a vertical thrust plate at the trailing end. This plate forms a stop end across the trench, is shaped at its lower edge to clear the pipe line or other work, and is connected to the frame by one or more double-acting rams of suitable size and stroke. The thrust plate operates in guides either between the trailing ends of the side shields or behind them and can be moved backward and forward in a horizontal direction. If desired provision may be made for adjusting the width of the thrust plate.

With the apparatus in its preferred form, the full power of the hydraulic excavator is transmitted to the thrust plate via suitable controls and rams. The ram speed required for efficient operation is low and in consequence a very substantial thrust is available for the movement of the frame from an excavator of even moderate horsepower.

The apparatus is designed so that the aforementioned operations may be carried out in a relatively short length of trench. With the thrust plate in its forward position the back acter working at the trench face may return the excavated spoil as fill directly behind the thrust plate, this being assisted if necessary by the use of an inclined chute. The necessity to deposit the spoil on the trench sides and therefore the increased pressures from this superimposed loading are eliminated and also the cost of refilling is reduced.

When a sufficient quantity of spoil has been returned behind the thrust plate a thrust sufiicient to cause forward movement of the shoring frame is applied via the rams. Thus the frame is moved forward against the ground pressures until the leading ends of the side shields, which are tapered to form cutting edges, bear against and enter the unexcavated trench face. Maximum thrust is then applied to the plate and the fill which has been returned is compacted against the resistance of the trench face.

The thickness of the vertical layers to be compacted, the amount of forward movement of the shoring frame and the force necessary for adequate compaction may be controlled by the operator, and for more effective compaction in certain types of material, provision is made for the vibration of the thrust plate.

In their preferred form the side shields are of sufiicient width to accommodate and protect the rams, slides and connections which transmit power to the thrust plate and also to enclose a number of well points which may be in a horizontal position and which are fixed internally along the lower edge of each shield. The lower sections of the shields in the vicinity of the well points are perforated to allow the ingress of water and the space between the inner faces of the shield and well-points is filled with a media suitably graded to prevent clogging with silts or other fine material which may be encountered during the trenching. The well points are connected to a vacuum pump of suitable size which may be mounted on or between the cross-members at the rear end of the machine and at the distance above the trench bottom which enables the system to operate most efiiciently. The suction head therefore remains constant regardless of the depth of trench.

The placing of a sufficient depth of permeable granular fill as a pipe bed assists in the dewatering operation and this system is very economical where this bed is specified as part of the pipe line construction.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawings showing one form of the invention.

In the drawings:

FIGURE 1 is a general arrangement of the apparatus and ancillary equipment in position of working;

FIGURE 2 is a plan view of FIGURE 1;

FIGURE 3 is an enlarged detail view of the thrust plate and rams shown in FIGURE 1;

FIGURE 4 is an enlarged cross sectional elevation of one of the rams shown in FIGURE 1; and

FIGURE 5 is a sectional end elevation taken on the line VV in FIGURE 4.

Referring to the drawings, and firstly to FIGURES 1 and 2, there is shown a rigid thrust plate 2 having connected thereto a plurality of double-acting, pressure-operated jack assemblies 4 (FIGURE 4), the rams of which are substantially horizontal to said plate 2. A plurality of horizontal walings 6 (corresponding in number to the number of jack assemblies 4) are secured to the jack assemblies and are held in spaced-apart relationship at their trailing ends by struts 8 and are supported at their leading ends by raking members and struts 7. Side plates 16 are secured to the walings 6 to form side shields, the leading ends of the side shields being tapered to form a cutting edge as indicated at 9 so that they may be forced into a trench face 10 by the operation of the jack assemblies 4. A bucket 12 of an excavator 14 is adapted to operate between the side plates 16. The waling 6, side plates 16 and struts 8 and 7 form a shoring frame indi cated generally at 15.

The walings 6 have vertical members 22 socketed therethrough which members are adapted to be extended with increasing trench depth and so support additional side plates which may be added as required.

A number of safety barriers 24 are socketed into the members 22 and move progressively forward with the apparatus, and a chute 26 is provided, the purpose of which chute will be explained hereinafter. A pipe-line 28 is shown lain in the formed trench.

Referring now to FIGURE 3, the thrust plate 2 is comprised of a plurality of vertical members 30 secured to horizontal members 32, the said horizontal members 32 having secured at each end thereof a jack assembly 4. Slotted in the vertical members 30 (which are preferably hollow square sections) are members 34 forming part of the aforementioned chute 26. It will be seen from this drawing that the vertical members 30 of the thrust plate 2 are of different length, this being to provide a recess 36 in the plate for allowing the apparatus to pass over the pipeline 28.

Referring now to FIGURES 4 and 5 which are detailed views of the jack assemblies are associated walings, there is shown an outer member 40 (constituting a waling 6), within which are arranged slides 42 and 44, the slide 42 being fixed to the horizontal member 32 of the thrust plate 2. Secured between the slides 42 and 44 is an end block 46 which is recessed at 48 to ease assembly and to house therein one end of a double-acting ram 52 of a jack assembly 4 located in waling 6. The said end of the ram 52 is housed in the end block 46 by means of a pin 54 passing through said ram end, the two ends of the pin being preferably spot welded to the end block 46. Bores 56 in the waling 6 are provided to facilitate entry of the pin 42.

The end of jack assembly 4, remote from the end block 46 is secured to the waling 6 by providing the end of jack assembly 4 with an eye or eyes 53 through which pass or passes a securing pin 60, spacer members 62 being provided to centralise the eye. The ends of said pin engage in the opposing walls of the waling 6 and side members 64 are provided to retain the pin in position and to give added strength to the waling 6.

Hydraulic fluid for the jack assembly 4 is supplied and returned via pipes 66 and 7 i). To afford protection to the pipe 7 i), and to restore the waling to its original strength, a member 72 is secured, preferably welded, to the underside of the waling 6. Hydraulic power is preferably supplied from the excavator 14. Jacking points 86 are provided for the adjustment to level as required.

In operation, the apparatus is set up as shown in FIG- URES 1 and 2 (after forming a section of the trench sufficiently large to accommodate the apparatus), the excavator 14 straddling a pilot trench '76 formed to expose and avoid damage to any existing services or pipes such as indicated at 78.

The required trench is formed by the bucket 12 of excavator 14 between the side plates 16, the spoil removed from the trench being formed being returned via chute 26 to fill the space behind the thrust plate 2.

Hydraulic power is then applied via the jack assemblies 4 to the thrust plate 2. Since the rearward (i.e. left in FIGURES 1 and 2) movement of the thrust plate 2 is limited by the returned spoil 82, the shoring frame 15 is caused to move forward a distance equal to or less than the length of the stroke of the rams 52 until the cutting edges 9 bear against or enter the trench face 10.

Further application of power to the jack assemblies 4 causes the thrust plate 2 to move rearwardly until the resistance of the returned spoil is equal to that of the trench face 10. This rearward movement of the plate 2 causes compaction of the returned spoil and this cornpaction may be assisted by vibrators 80 provided on the thrust plate 2.

The action of the jack assemblies 4 is then reversed causing the thrust plate to be moved forward to its position shown in FIGURE 1, since the weight of the thrust plate 2 is less than that of the shoring frame 15 and associated equipment. The recess 36 in the thrust plate 2 prevents the latter from fouling the pipeline 28.

The cycle of operations is then repeated until a sufficient length of trench has been formed for the addition of a further pipe to the pipeline 28.

When the apparatus reaches the services or pipes 78 which may obstruct the upper section of the trench, the members 22 (and in turn chute 26) and any of upper side plates 24 may be raised or removed as required and reinserted at the other side of said services, whereafter operation may proceed as described above.

It will be appreciated that the thrust plate described serves not only as an anchorage for the forward thrust and as a compactor, but also as a progressive end stop for the trench filling in a vertical or near vertical plane, and decreases the length of trench in which work is taking place to such an extent that the spoil is readily returnable to a position behind said plate which thus avoids the necessity of the double handling of the spoil (which is at present orthodox procedure), thereby increasing the efiiciency of trench forming operation with a consequent reduction in operating costs.

As previously mentioned, members 17 at the bottom of the side shields may house one or more well-points for working in water bearing ground conditions, the wellpoints being connected to a suitable vacuum pump.

I claim:

1. A trench shoring frame comprising a pair of opposed side walls in spaced relation and positioned in the trench closely adjacent the walls thereof to shore the same, a plurality of cross members extending between the opposed side walls, said side walls and cross members defining a working zone communicating between the top and the bottom of the frameand the forward end of the frame, a rigid thrust plate located at the trailing end of the work zone end extending transversely relative to the direction of spacing of said side walls and trench, said thrust plate being dimensioned to close off a major portion of the trailing end of the working zone, and a plurality of jacks each coupled between said thrust plate and said frame, expansion of said jacks urging the thrust plate against back fill to compact the back fill until the resistance offered thereby causes continued expansion to thrust the shoring frame and the working zone forward.

2. A trench shoring frame as claimed in claim 1 wherein said side walls comprise adjustable side plates which are secured by horizontally disposed waling means to the frame and are tapered to form an exterior cutting edge.

3. A trench shoring frame as claimed in claim 2 including a chute which is detachably connected to said waling means by vertical connecting members.

4. A trench shoring frame as claimed in claim 2 wherein said side plates are provided with removable vertical members which are detached for the passing of obstructions.

5. A trench shoring frame as claimed in claim 4 wherein the side plates are provided with well connections and a vacuum source is connected to said well connections for working in water-bearing ground.

References Cited UNITED STATES PATENTS 654,426 7/ 1900 Washington 61-41 977,016 11/1910 Johnson 61-39 1,234,716 7/1917 Bager 61-41 2,865,178 12/1958 Wicke 61-41 2,908,140 10/1959 Everson 617-41 3,089,310 5/1963 Torti 61-41 3,159,978 12/1964 DeLillo 61-41 3,204,415 9/1965 Hill et a1 61-41 JACOB SHAPIRO, Primary Examiner.

DAVID J. WILLIAMOWSKY, Examiner. 

